Of vanadium ore is rich in resources, mainly minerals for the vanadium-titanium magnetic iron ore. As the market price of vanadium rises, carbon shale vanadium ore and siliceous vanadium ore are also fully utilized. The sodium roasting in the vanadium extraction process has been banned due to serious environmental pollution. The use of sodium-free roasting to extract vanadium is the development direction of the vanadium extraction process. China has a vast territory and complex ore properties. The study of its properties and parameters for ore properties is the core of successful vanadium extraction. In this paper, the characteristics of a carbon-silica vanadium mine in Shaanxi are studied in detail, and the roasting-leaching process is studied in detail, and the extraction, vanadium precipitation and calcination processes are completed, and the test has achieved good results.
I. Mineral analysis and chemical composition
The mineral analysis results of the mine indicate that the main mineral composition of the mine is chalcedony, quartz , clay minerals, a small amount of feldspar , limonite, hematite, calcite . Vanadium mainly occurs in clay mines, and may be mainly kaolin and yoshi. X-rays are difficult to accurately distinguish the specific vanadium content of each mineral. The results of phase analysis indicated that vanadium was mainly replaced by V(III) isomorphism in the form of a coordinating form of trivalent aluminum present in aluminosilicate minerals accounting for 9.38%. Among them, vanadium accounts for 32.81% of iron oxide and clay minerals, vanadium accounts for 61.72% of mica type minerals, and 5.47% of vanadium in tourmaline and garnet. The vanadium has a fine grain size and a variety of distribution. The chemical analysis results of the ore are shown in Table 1.
Table 1 Analysis results of raw ore chemical composition %
element | V 2 O 5 | FeO | Fe 2 O 3 | MnO | K 2 O | Na 2 O | MgO | CaO | C | Cu |
content | 1.16 | 0.93 | 2.62 | 0.005 | 0.52 | 0.071 | 2.14 | 0.70 | 1.08 | 0.005 |
element | Ph | Bi | Ni | Mo | S | Al 2 O 3 | P 2 O 5 | SiO 2 | Moisture | Burnout |
content | 0.005 | 0.005 | 0.026 | 0.028 | 0.20 | 2.92 | 0.48 | 54.57 | 0.32 | 8.30 |
Second, roasting - leaching process research
There are three kinds of roasting-leaching processes commonly used in carbon siliceous vanadium ore, namely acid leaching, alkali leaching, and water immersion. The test carried out three comparisons of vanadium extraction schemes.
(1) Comparison of acid leaching, alkali leaching and water immersion test schemes
1. Acid leaching
Acid leaching includes direct acid leaching and roasting acid leaching. The effects of the two schemes on the leaching results under different conditions were compared. Refer to the relevant data test basic parameters set to: grinding fineness of -74μm 71.5%, granulation Φ8 ~ 20mm, roasting time 2h, temperature 850 ° C, the amount of acid containing a small amount of oxidant is 12% of the original ore sample, the leaching solution solid ratio of 1.2 1: leaching time 12h, temperature 85 ~ 90 °C. The results are shown in Table 2.
Table 2 Test results of different acid leaching schemes %
test Serial number | Leaching Slag rate | Slag inclusion V 2 O 5 | Slag meter V 2 O 5 Leach rate | Remarks |
1 | 93 | 0.89 | 22.64 | Direct acid leaching |
2 | 97 | 1.09 | 1.19 | Add 10% H 2 O 2 direct acid leaching |
3 | 94 | 0.53 | 53.44 | Direct acid leaching with 2% NaClO 3 |
4 | 98 | 0.75 | 30.53 | Acid leaching after 5% lime granulation |
5 | 97 | 0.085 | 92.49 | Acid immersion after blank roasting |
The test results show that: (1) The leaching rate of direct acid leaching vanadium is only 22.64%. By adding different oxidants in the leaching process, the valence state of vanadium can be greatly affected. The leaching rate of adding 2% NaClO 3 vanadium can reach 53.44%. It may be that the addition of NaClO 3 makes the conversion of low-priced vanadium into high-valence vanadium easy to leach, while the vanadium that cannot be converted mostly exists in trivalent; the addition of H 2 O 2 leads to the deterioration of vanadium leaching results, which needs further study.
(2) Two kinds of processes were studied in the roasting-acid leaching test. The leaching rate of vanadium under calcification roasting conditions was 30.53%. Compared with the direct acid leaching vanadium leaching rate, the effect is not obvious. Under the acid leaching condition after blank roasting, the vanadium leaching rate reaches 92.49%, and the blank roasting-acid leaching process is better.
2. Alkali dip and flooding
Alkali leaching is often carried out by calcination, that is, calcium oxide is added during the calcination process. The leaching is carried out in a carbonate lye to form a calcium carbonate precipitate and a sodium vanadate salt. The immersion liquid used in the test was a 10% sodium carbonate solution; the water immersion was carried out by blank roasting. Other conditions are the same as acid leaching. The results are shown in Table 3.
Table 3 Results of alkali leaching and water immersion test %
test Serial number | Leaching Slag rate | Slag inclusion V 2 O 5 | Slag meter V 2 O 5 Leach rate | Remarks |
6 | 99 | 0.78 | 27.01 | Add 5% calcium oxide roasting alkali soak |
7 | 99 | 0.76 | 27.26 | Add 10% calcium oxide roasting alkali soak |
8 | 97 | 0.25 | 77.91 | Blank roasting water immersion |
The test results show that the leaching rate of the mine under the blank roasting-water immersion condition is 77.91%, and the leaching result is obviously better than the alkali leaching process.
It can be seen from the comparison of the three calcination-leaching processes that the carbon silic vanadium ore can achieve satisfactory leaching effect by direct acid leaching and water immersion in blank roasting, although water immersion helps to eliminate impurities such as iron and magnesium . Considering that the acid leaching rate is higher than about 15% of water immersion, the blank baking-acid leaching scheme is more economical.
(2) Research on process conditions
1. Effect of roasting temperature
In the vanadium extraction process, the calcination temperature of vanadium ore is generally 750-900 ° C, and the calcination temperature range is 650-950 ° C. The results are shown in Figure 1.
Figure 1 Effect of calcination temperature on leaching rate
It can be seen from Fig. 1 that the optimum calcination temperature of the ore is 800 °C. When the temperature is low, the oxidation of low-valent vanadium is insufficient. When the temperature exceeds 800 °C, the leaching rate decreases because some clinker is sintered, making it difficult to extract vanadium. Big.
2, the impact of roasting time
The calcination time was selected to be 1, 1.5, 2 h, and the results are shown in Fig. 2.
Figure 2 Effect of roasting time on leaching rate
It can be seen from Fig. 2 that the optimum baking time is 1.6 h. When the time is too long, not only the energy consumption is increased, but also the sintering is caused.
3. Influence of grinding fineness
Grinding fineness selection: -74μm 50%, 60% 70%, 80% curve, the results are shown in Figure 3.
Figure 3 Effect of grinding fineness on leaching rate
It can be seen from Fig. 3 that the fineness of grinding has a great influence on the leaching rate. As the fineness increases, the leaching rate increases. When the -74μm reaches 70%, the leaching rate no longer increases, and the best grinding The fineness is -74 μm 70%.
4. Effect of acid dosage on leaching rate
The test selected the concentration of concentrated sulfuric acid containing oxidant by 4%, 6%, 8%, and 12%. The test results are shown in Figure 4.
Figure 4 Effect of sulfuric acid dosage on leaching rate
It can be seen from Fig. 4 that the acid dosage is 6%, the leaching rate of vanadium reaches 94.03%, and when the dosage is 12%, the leaching rate is 94.39%, and the added value is not large. From the economic and leaching indexes, the optimum amount of sulfuric acid is 6%.
5, leaching temperature effect
The leaching temperature test results are shown in Figure 5.
Figure 5 Effect of leaching temperature on leaching rate
It can be seen from Fig. 5 that the leaching effect is good at a normal temperature of 30 ° C, the leaching rate is 93.36%, 60 ° C, and the leaching rate is at most 95.30%. From the aspects of process, energy consumption and leaching rate, it is generally normal temperature.
Third, extraction - precipitation vanadium - calcination process research
Extraction using phosphoric acid, phosphate and kerosene, back-extracted with concentrated sulfuric acid to 1.5M, two extraction - back extracted extraction rate reached 97.69%, less extraction section number extraction effect is obvious; vanadium precipitation adding ammonia to adjust pH during oxidation The rate of vanadium precipitation is 98.28%. The final product of vanadium pentoxide can be obtained by calcination for 1-3 hours.
Fourth, the conclusion
(1) The vanadium ore has a simple composition, mainly SiO2, and most of the vanadium is present in the clay ore with low impurity content. Therefore, the roasting-leaching and impurity removal processes are relatively simple.
(2) The vanadium ore can be subjected to blank roasting-normal temperature acid leaching and blank roasting-water immersion process, but the former has a higher leaching rate. The blank roasting-acid leaching is non-polluting. The optimum process parameters are: calcination temperature 800 ° C, calcination time 1.6 h, grinding fineness -74 μm 70%, optimum leaching acid dosage 6%. Under this process and parameters, the leaching rate is 93.36%.
(3) After blank roasting-acid leaching, extraction-precipitating vanadium-calcining vanadium, the final vanadium recovery rate is greater than 74%, and the vanadium pentoxide grade is greater than 98%, in line with product standards.
Cardio Training,X Bike,Sports Treadmill,Cycling Bike
Hangzhou Gymbo Sports Co., Ltd , https://www.gymbosports.com